The present invention relates to rigid-rod monomers and polymers for use in applications such as rapid prototyping, composites and adhesives.
In recent years, monomers have been developed for use as building materials in rapid prototyping by stereolithography and other processes as well as for use in polymer composites and adhesives. Such monomers may be used in the liquid crystal phase, which makes it possible to create layered structures with anisotropic mechanical properties by varying molecular orientation during the process of forming the polymer. However, current stereolithography methods are performed at ambient temperatures, while it is desirable for the monomers to be used in applications which require elevated temperatures, and the upper-use temperature of the cured resins needs to approach or exceed 200xc2x0 C. as disclosed in related copending U.S. application Ser. No. 09/128,078, the disclosure of which is hereby incorporated by reference.
Accordingly, there is still a need in the art for the development of liquid crystalline monomers for use in rapid prototyping, composite and adhesive applications and composite applications which form highly crosslinked polymers having high glass transition temperatures.
The present invention meets those needs by providing diacrylate monomers of two types, i.e. those as shown in formula I below and those as shown in formula II below. The monomers can be photocured through the end groups and then thermally post cured through the acetylene groups. The result is a highly crosslinked polymer having an effective glass transition temperature well above 200xc2x0 C.
The structural formulas for Monomer I and Monomer II are as follows: 
where X1, X2=H, F, CH3, OCH3, Cl, NO2 or NH2,
where Y1, Y2=H, F, CH3, OCH3, Cl, NO2 or NH2,
where Z=CH2, NH, O, S or SO2,
where R1 is none, O, S or Cxe2x89xa1C,
where R2 is none, O, S or Cxe2x89xa1C, and
where n is 0-20. 
where X=CH2, NH, O, S or SO2,
where R is acrylate, glycidyl or epoxy, and
where n is 0-20.
Included within the preferred species of Monomer I are those having the following formulas: 
where n=3 or 6 and where in
Monomer IA1 Xxe2x95x90Yxe2x95x90H,
Monomer IA2 Xxe2x95x90Yxe2x95x90F,
Monomer IA3 Xxe2x95x90F, Yxe2x95x90H. 
where A is: 
CHxe2x95x90CHxe2x80x94, xe2x80x94C(CH3)xe2x95x90CHxe2x80x94, xe2x80x94CO2xe2x80x94, xe2x80x94CHxe2x95x90Nxe2x95x90, xe2x80x94Nxe2x95x90Nxe2x80x94, and
X=H, F, CH3, OCH3, Cl,
m=0-20,
R1=none, O, S, and
Y=H, F, CH3, OCH3, Cl,
n=0-20,
R2=none, O, S.
Included within the preferred species of Monomer II are those having the following formula: 
where R in IIB-IIE is acrylate, glycidyl or epoxy.
Accordingly, it is a feature of the present invention to provide novel rigid rod monomers and polymers for use in rapid prototyping, composites and adhesives, and more particularly to provide two types of diacrylate monomers and resulting polymers for such uses. This, and other features and advantages of the present invention will become apparent from the following detailed description and the appended claims.